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Pamenlarge User	Manual(0)			     Pamenlarge	User Manual(0)

       pamenlarge - Enlarge a Netpbm image N times

       pamenlarge  [-scale=integer] [-xscale=integer] [-yscale=integer]	[file-

       pamenlarge N [pnmfile]

       This program is part of Netpbm(1).

       pamenlarge reads	a Netpbm image	as  input,  replicates	its  pixels  N
       times,  and  produces a Netpbm image as output.	The output is the same
       type of image as	the input.

       If you enlarge by a factor of 3 or more,	you should probably add	a  pn-
       msmooth step; otherwise,	you can	see the	original pixels	in the result-
       ing image.

       For PBM images, pamenlarge uses special fast algorithms for scale  fac-
       tors  up	 to  10.   For larger factors, it uses a simple	but slow algo-
       rithm.  As a result, you	can often get a	significantly faster scale  by
       running	pamenlarge  multiple  times.   For example, enlarging by 3 and
       then by 5 is faster than	enlarging once by 15.  And because  the	 algo-
       rithms  are different for the different scale factors, some faster than
       others, the order matters too.  For example, the	following examples all
       produce	the  same  output -- an	image 15 times bigger on edge than the
       input --	but at different speeds, each being faster than	 the  one  be-

	    $ pamenlarge -scale=15 test.pbm
	    $ pamenlarge -scale=5 test.pbm | pamenlarge	-scale=3
	    $ pamenlarge -scale=3 test.pbm | pamenlarge	-scale=5

       The  special fast cases for factors up to 10 have existed since Release
       10.50 (March 2010).  The	special	cases for 1, 2,	3, and 5  go  back  to
       Release	10.41  (December  2007).   Before  10.41, there	are no special
       scale factors and PBM enlargement is significantly  slower  than	 today
       for all scale factors.

       pamenlarge  can	enlarge	 only by integer factors.  The slower but more
       general pamscale	can enlarge or reduce by arbitrary factors.   pamscale
       allows  you to enlarge by resampling, which gives you smoother enlarge-
       ments.  But it is much slower.

       pamstretch is another enlarging program that enlarges by	 integer  fac-
       tors.   It  does	 a simple kind of resampling that gives	you a smoothed
       enlargement with	less computational cost.

       pbmreduce can reduce by integer factors,	but only for PBM images.

       As with most Netpbm programs, you can give the input file  name	as  an
       argument	 or  omit  that	 argument and have it come from	Standard Input
       (and you	can specify '-'	for the	argument to specify Standard Input ex-

       You can also specify the	scale factor as	an argument, for backward com-
       patibility, but the preferred way to do that is with a  -scale  option,
       because	it  is easier to remember and read that	way.  The scale	factor
       argument	goes before the	file name argument.



	      These specify the	scale factor.  -xscale specifies the  horizon-
	      tal  scale  factor;  -yscale specifies the vertical scale	factor
	      and -scale specifies both.

	      If you specify -xscale but  not  -yscale,	 pamenlarge  does  not
	      scale  vertically	 (i.e.	the  vertical scale factor is 1).  The
	      converse applies if you specify -yscale and not -xscale.

	      You cannot specify -scale	and also -xscale or yscale.

	      You must specify at least	one of these options, unless  you  use
	      the  deprecaated method of specifying the	scale factor via argu-

	      These options were all new in Netpbm 10.86 (March	2019).	Before
	      that, use	the scale argument.

       pamenlarge was new in Netpbm 10.25 (October 2004).  It is designed as a
       replacement for pnmenlarge by Jef Poskanzer, which was  in  Pbmplus  as
       far  back as 1989.  The major difference	is that	pamenlarge can enlarge
       PAM format images in addition to	PNM.

       pbmreduce(1), pamscale(1), pamstretch(1),  pbmpscale(1),	 pnmsmooth(1),

       Copyright (C) 1989 by Jef Poskanzer.

       This  manual  page was generated	by the Netpbm tool 'makeman' from HTML
       source.	The master documentation is at

netpbm documentation		07 January 2019	     Pamenlarge	User Manual(0)


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